CN108020522B

CN108020522B - Device for determining the concentration of at least one gas component in a respiratory gas mixture

Info

Publication number: CN108020522B
Application number: CN201711033155.5A
Authority: CN
Inventors: P.德雷耶; G.施泰纳特; B-M.迪克斯; R-P.雅格比
Original assignee: Draegerwerk AG and Co KGaA
Current assignee: Draegerwerk AG and Co KGaA
Priority date: 2016-10-28
Filing date: 2017-10-30
Publication date: 2021-03-09
Anticipated expiration: 2037-10-30
Also published as: JP6538802B2; EP3315947A1; JP2018077222A; EP3315947B1; US10502682B2; CN108020522A; DE102016012970A1; US20180120224A1

Abstract

The invention relates to a device for determining the concentration of a gas component, comprising a radiation source for emitting optical or thermal radiation in the wavelength range of infrared light, a detector arrangement with at least two detector elements, which are suitably designed in an angle component, for detecting the optical or thermal radiation generated by the radiation source, and two associated detector elements, filter elements. At least one of the two detector elements is oriented in an angle mechanism about a vertical axis such that an overlap region is formed as determined by the angle mechanism. The overlap region results in attenuation in the light diffusion, for example due to gas molecules or moisture, acting on the two detector elements and thus equalizing the attenuation in the light diffusion with respect to the concentration measurement.

Description

Device for determining the concentration of at least one gas component in a respiratory gas mixture

Technical Field

The invention relates to a device for determining the concentration of at least one gas component in a breathing gas mixture. The device for determining the concentration of a gas component in a breathing gas mixture is used in particular for determining the concentration value of carbon dioxide exhaled by a patient.

Background

DE 10047728B 4 describes a sensor for measuring carbon dioxide, nitrous oxide and anesthetic gases. A detector assembly consisting of four filter elements with associated detector elements is shown. The combination of filter elements and detector elements is around the radiation mixing system. Such a radiation mixing system implemented in a multispectral sensor is shown in EP 0536727B 1. Such a sensorDevices in clinical work, e.g. for monitoring instruments and so-called C0₂Mainstream sensor or also C0₂In a lateral flow sensor. US 5261415B 2 shows C0₂A mainstream monitoring sensor. In the cuvette carrying the breathing gas, an insert is arranged, in which in turn an infrared optical measuring system is arranged. It can be seen from EP 0536727B 1 how complex optical components must be designed and arranged to achieve effective radiation mixing. The purpose of the radiation mixing is to make locally occurring contaminations effective symmetrically not only in the reference channel but also in the measurement channel. This is necessary in order to ensure that the ratio of the measurement channel to the reference channel is ensured in all operating points in such a way that contamination, water vapor and aging effects of the detector element can be permanently compensated for during operation. A disadvantage of the solution as shown in EP 0536727B 1 is that the radiation mixes thereby causing signal attenuation, since the infrared light has to be deflected and reflected multiple times in the cuvette. This signal attenuation results in a poor signal-to-noise ratio (SNR). In order to achieve the necessary measurement value resolution, the increase in the measurement effect must be compensated by an increase in the absorption length. The increase in absorption length results in an enlargement of the structural design. Furthermore, the requirement of radiation mixing and the large number of components involved therein also has a negative effect on the complexity and high tolerance requirements of the components involved in the multispectral sensor of EP 0536727B 1 (tolerance chain) and the resulting high manufacturing costs.

Disclosure of Invention

Based on the prior art mentioned above and the disadvantages described there, it is the object of the present invention to provide a device for determining the gas concentration of at least one gas component in a breathing gas mixture which is distinguished by simple but effective radiation mixing and low space requirements at relatively favourable production costs.

This object is achieved by a device for determining the concentration of at least one gas component in a breathing gas mixture having the features of the invention.

Advantageous embodiments of the invention result from the invention and are explained in more detail in the following description, in part, with reference to the figures.

According to the invention, the following components are provided in the device for determining the concentration of at least one gas component in a breathing gas mixture:

a radiation source which is suitable and designed for radiation of optical or thermal radiation in the wavelength range lambda (λ 1) =3000nm to lambda2 (λ 2) =10000nm,

at least two detector elements, which are suitably configured for detecting optical or thermal radiation generated by the radiation source,

-at least two band-pass filter elements arranged on the detector element,

-a control unit.

Light radiated by the radiation source is emitted from the radiation surface of the radiation source along the vertical axis of the device substantially at right angles to the direction of radiation.

The wavelength range from lambda1 (λ 1) =2.5 μm to lambda2 (λ 2) =14.0 μm of the radiation source makes it possible to carry out infrared optical measurements of nitrous oxide concentrations, carbon dioxide concentrations and different hydrocarbons, such as, for example, volatile anesthetic gases or methane.

The detector elements are designed, for example, as semiconductor detectors, pyroelectric detectors (pyroelectric detectors), pyroelectric detectors (thermopiles, thermocouples), as thermal detectors (bolometers) and as a combination of semiconductor detectors and thermal detectors. The detector element is designed for detecting light for infrared radiation in the infrared wavelength range, wherein absorption by gases such as carbon dioxide is typically provided.

The bandpass filter element is designed, for example, as an optical interference filter in the form of an interference layer on a substrate. They transmit light within a defined wavelength range.

The arrangement of the band-pass filter elements is designed such that infrared radiation radiated by the radiation source passes through the band-pass filter elements before the detector elements on the direct radiation path or also on the indirect radiation path, for example by deflecting the infrared radiation by means of a reflective element or a mirror assembly in the radiation path. At least one of the at least two band-pass filter elements is configured to be optically transparent to infrared radiation in a wavelength range, which is absorbed by the measurement gas.

The detector element, on which the band-pass filter element is arranged, is a so-called measurement channel in the device for determining the concentration of at least one gas component in a breathing gas mixture.

At least one of the at least two band-pass filter elements is configured to be optically transparent to infrared radiation in the wavelength range, which is not or only slightly absorbed by the measurement gas.

The detector element on which the band-pass filter element is arranged forms a so-called reference channel in the device for determining the concentration of at least one gas component in a respiratory gas mixture.

The measurement gas, which is also commonly referred to as target gas, is for example carbon dioxide or nitrous oxide and various gaseous organic compounds such as methane or volatile anesthetic gases such as halothane, isoflurane, desflurane, enflurane.

In an apparatus for determining the concentration of at least one gas component in a breathing gas mixture, measured values of a measurement channel and a reference channel are detected by a control unit and are proportional to one another. A quotient of the measured value of the detected measurement channel and the measured value of the detected reference channel is usually formed and indicates the degree of measurement of the concentration of the gas in the device for concentration determination, i.e. the concentration of the amount of gas in the radiation path.

The spatial arrangement of the at least two detector elements and the band-pass filter elements relative to a radiation source or relative to a radiation axis is carried out in such a way that at least one of the two detector elements with at least one of the band-pass filter elements arranged on the at least two detector elements is arranged in an angle component at an angle in the range of 5 ° to 80 ° relative to an axis running through the radiation source parallel to or in the same direction as the direction of the radiation source.

At least two detector elements with at least two bandpass filter elements arranged thereon form at least two angle components with respect to an axis extending perpendicularly from the radiation plane of the radiation source. At least two angle components with at least two detector elements and band-pass filter elements arranged on the at least two detector elements together form a detector component. The at least two angle assemblies are arranged at an angle relative to an axis extending perpendicularly from the radiation plane of the radiation source such that the axis extending perpendicularly from the radiation plane of the radiation source extends between the at least two angle assemblies.

At least one of the angle assemblies is not arranged and designed here in an orientation parallel to the radiation surface of the radiation source, but is arranged at an angle relative to an axis extending perpendicularly from the radiation plane of the radiation source such that the axis extending perpendicularly from the radiation plane of the radiation source extends between the at least two angle assemblies and the at least one of the angle assemblies is inclined at an angle towards the axis extending perpendicularly from the radiation plane of the radiation source.

In a preferred embodiment, at least one of the angle assemblies is arranged here in an orientation parallel to the radiation surface of the radiation source, such that an axis extending perpendicularly from the radiation plane of the radiation source extends between the at least two angle assemblies, and at least one of the angle assemblies is arranged at right angles of 90 ° to the axis extending perpendicularly from the radiation plane of the radiation source.

In a particular embodiment, all of the at least two angle assemblies are arranged at an angle to an axis extending perpendicularly from the radiation plane of the radiation source such that the axis extending perpendicularly from the radiation plane of the radiation source extends between the at least two angle assemblies, and each of the at least two angle assemblies is inclined in each case toward the axis extending perpendicularly from the radiation plane of the radiation source. The inclination of each of the at least two angle assemblies relative to the angle of an axis extending perpendicularly from the radiation plane of the radiation source between the at least two angle assemblies can be different or almost identical to each other. In this way, a design of 60 ° for one of the at least two angle components and 30 ° for another of the at least two angle components and of 45 ° for both of the at least two angle components relative to an axis extending perpendicularly from the radiation plane of the radiation source between the at least two angle components can be achieved.

This design of the at least two angle components results in the at least two angle components being inclined to each other. Such a tilting provides the advantage that between the at least two detector elements there is a region between the radiation paths from the radiation source to the detector elements.

The overlap region is produced perpendicularly from the plane of the arrangement of the detector elements in the direction of the radiation source. Due to the angle, for example, gas molecules, water vapor, condensate or also other contaminants such as dust are located in the radiation path of the two detector elements, so that the influence of water vapor, condensate or also other contaminants in the measurement signal is manifested, for example, as an amplitude decay of the measured values in the measurement channel as well as in the reference channel. This creates the possibility of eliminating the influence of moisture (water vapor, condensate) or other contaminants by means of the proportional formation of the signals of the reference channel and the measurement channel. The region of overlap may be defined by a selection of angular components of the measurement channel-detector element/band-pass filter element and the reference channel-detector element/band-pass filter element and respective angles with respect to an axis extending between at least two of the angular components.

In conjunction with the selection of the vertical spacing between the radiation source and the angle assembly, it is furthermore possible to vary and define the design of the overlap region with spatial dimensions, planar overlap, effective overlap volume for the measurement gases.

By the design of the angle arrangement and the vertical spacing described above, in an apparatus for determining the concentration of at least one gas component in a breathing gas mixture, it is possible in an advantageous manner, for example, to take into account the absorption behavior of the measurement gas to be measured and also to influence the desired concentration range of the measurement gas.

In a preferred embodiment, each of the at least two detector elements is arranged with a first spacing l1 relative to a vertical axis extending between the at least two angle assemblies, preferably centrally, which first spacing is in the range of 0.1mm to 10.0 mm.

In a preferred embodiment, each of the at least two bandpass filter elements arranged on the at least two detector elements is at a second distance i from a perpendicular axis extending between the at least two angle components, preferably centrally₂The arrangement is such that the second pitch is in the range 0.1mm to 10.0 mm.

In a preferred embodiment, the at least two angle elements are arranged spaced apart from each other in the range of 0.1mm to 10 mm.

In a further preferred embodiment, the detector arrangement with the at least two detector elements and the at least two band-pass filter elements arranged on the at least two detector elements is arranged at a third distance/₃Arranged opposite the radiation source, the third distance l₃In the range of 0.1mm to 10.0mm, wherein the third pitch i₃Expressed as the spacing directly in this region or along the axis extending between the at least two angle components.

In a preferred embodiment, the detector arrangement with the at least two detector elements on the same side and the at least two bandpass filter elements arranged on the at least two detector elements is arranged adjacent to the radiation source, and the radiation source is arranged between the at least two detector elements with the at least two bandpass filter elements arranged on the at least two detector elements on the center of the axis extending between the at least two angle arrangements.

In this case, a third distance l is provided opposite the radiation source and opposite the at least two detector elements with the at least two band-pass filter elements arranged thereon_3'At least one optically reflective, preferably planar, reflective element is arranged, the third distance l_3'In the range of 0.1mm to 5.0mm, wherein the third pitch l_3'Expressed as the spacing directly in this region or along the axis extending between the at least two angle components.

The band-pass filter element is designed for optically filtering infrared light in a transmission range of wavelengths in the range of 2.5 μm to 14 μm.

With such a band-pass filter element, a penetration region for gases as listed in table 1 below can thus be realized.

Numbering	Type of gas	Range of wavelengths
				1	Carbon dioxide	4.2 to 4.4 microns	CO2
	Nitrous oxide	7.8 to 9.0 microns	N2O
					Methane	3.1 to 3.5 microns	CH4
	Ethane (III)	3.2 to 3.6 microns	C2H5
					Fluoroalkane	8 to 10 microns	C2HBrCIF3
	Isofluoroethers	8 to 10 microns	C3H2OCIF5
					Anfluoroether	8 to 10 microns	C3H2CIF5O
	Sevoflurane	8 to 10 microns	C4H3F7O
					Desflurane	8 to 10 microns	C3H2F6O
	Acetone (II)	8 to 10 microns	C3H6O
					Ethanol	8 to 10 microns	C2H5OH

Table 1.

During the administration of anesthesia, for example at the time of surgery, the gases nitrous oxide, halothane, isoflurane, sevoflurane and desflurane are used to anesthetize a patient, acetone becoming a possible metabolite of the patient and thus being contained, for example, in the exhaled air of a diabetic patient. Ethanol may be found, for example, in the air exhaled by an alcohol patient.

In a further preferred embodiment, the radiation source is configured as a surface emitter or as a thin-film emitter or light-emitting diode (LED) with a substantially planar radiation surface. Such surface emitters or thin-film emitters with planar radiating elements or light-emitting diodes (LEDs) are designed with a substantially planar design of the radiating surface in order to achieve uniform radiation over the radiating surface.

The radiation surface of the surface emitter or of the thin-film emitter and of the substantially planar light exit surface of the light-emitting diode is preferably designed to be 2.0mm²To 10mm²Within the range of (1).

In a further preferred embodiment, the detector element is designed as a thermopile or thermocouple.

In a further preferred embodiment, the detector element is designed as a semiconductor detector, for example as an InAsSb detector (indium-arsenic-antimony detector).

In a further preferred embodiment, the detector element is configured as a pyroelectric detector.

In a further preferred embodiment, the detector element is configured as a bolometer.

As advantages of thermocouples, thermopiles, pyroelectric detectors and bolometers, it should be mentioned that they can be manufactured economically and efficiently and can be used as heat detectors in a broad wavelength range of 3 to 10 μm.

As an advantage of semiconductor detectors, it should be mentioned that their measurement sensitivity can be matched well to the desired wavelength range.

In a further preferred embodiment, a plurality (more than two) of detector elements with bandpass filter elements respectively arranged thereon are arranged together around the center point in a circular or rectangular arrangement, for example of the frustum side.

The frustum is shaped so that it appears as a funnel having the shape of a frustum beyond the head or having the shape of a clover or tulip. In a special variant of this further preferred embodiment, the detector arrangement has four angle elements in the form of four sides of a frustum of a rectangle or square in spatial arrangement with detector elements and bandpass filter elements. In this way, a measurement with a plurality of measurement gases can be detected, for example, by means of three measurement channels relative to a reference channel.

This makes it possible to advantageously carry out, for example, the measurement of carbon dioxide (CO 2), nitrous oxide (N2O), and volatile anesthetics such as halothane (C2 HBrCIF 3), isoflurane (C3H 2OCIF 5) relative to the reference channel in a single device for determining the concentration of at least one gaseous component in a respiratory gas mixture.

In a further preferred embodiment, in the device for determining the concentration of at least one gas component in a breathing gas mixture, the detector arrangement and the radiation source form a flow guide element which is suitable for guiding the inhalation gas and/or the exhalation gas in order to guide the flow in the flow channel. The flow-guiding element guides the inhaled and/or exhaled gas as a main flow and in this case passes through the radiation source and the radiation path to the at least two angle modules with the at least two detector elements and the bandpass filter elements arranged thereon. Here, the gas concentration is detected in the main stream.

One embodiment of this type of embodiment is a device for measuring carbon dioxide in the exhaled air of a patient, for example, as a component directly at the mouth region of the patient, which is generally referred to as the so-called "mainstream C0₂A sensor ".

Another embodiment of this embodiment is an analysis device, for example for measuring carbon dioxide and other exhaled gases, in particular anesthetic gases. In the exhalation air of the patient, the measurement is carried out by a set-up in which the gas quantity in the mouth region is continuously pumped or conveyed from the mouth region directly in the mouth region by a pump arranged in the analysis device via a small-diameter hose to the analysis device, and the gas quantity is analyzed there with regard to the gas composition and the gas concentration. This measurement method is generally referred to as so-called "aspiration gas measurement" or as so-called "sidestream anesthetic gas monitoring".

In a further preferred embodiment, the device for determining the concentration of at least one gas component in a breathing gas mixture has a flow guide element for guiding the flow in a flow channel, in or at which the detector arrangement, the radiation source and the optical reflection element are arranged. The flow-guiding element has a component projecting into the flow channel. A portion of the inspired and/or expired gas is guided through the component as a side stream or side stream and passes there through a radiation path between the optically reflective element and at least two angle assemblies with at least two detector elements and at least two band-pass filter elements arranged thereon. Here, the gas concentration is detected in the main flow portion in the side flow or the side flow.

Such a component may-for example in the form of a so-called T-piece-guide a portion of the main flow in the center of the flow guide element in such a way that a measurement gas is used for concentration measurement, which measurement gas represents the amount of gas in the center of the flow guide element.

Such a component can, for example, be in the form of a lateral arrangement on the flow-guiding element at the edge of the flow-guiding element, guide a portion of the main flow in the center of the flow-guiding element in such a way that a measurement gas is used for the concentration measurement, which measurement gas represents the amount of gas in the lateral edge of the flow-guiding element.

For the measurement of applications in the field of anesthesia, the size of the device for determining the concentration of at least one gas component in the respiratory mixture plays a non-trivial role-in particular for "sidestream" applications. In combination with the structural dimensions of the radiation source with the structural dimensions of the smaller measurement volume in the region of the detector elements (bolometer, microbolometer array, pyroelectric detector, thermocouple, thermopile, semiconductor detector) and the band-pass filter element, preferably 2.0mm, and the arrangement of the at least two detector elements at a distance of preferably less than 10mm from one another, a distance l3 between the radiation source and the detector element or band-pass filter element in the preferred range of 0.1mm to 10mm and a distance l3 between the radiation source and the reflector element (mirror) in the range of 0.1mm to 5.0mm result in a device for determining the concentration of at least one gas component in a respiratory gas mixture having structural dimensions of the smaller measurement volume in the region of less than 0.4ml, preferably 0.05 to 0.2²To 10.0mm²With the detector element and the band-pass filter element preferably at 0.5mm²To 20mm²Of (2) is provided.

In the case of "aspirated gas measurement" with an aspirated volume flow of 50ml/min to 200ml/min by means of a pump arranged in the device, it follows that the exchange time of the measurement volume in the device for determining the concentration of the at least one gas component in the breathing gas mixture is 0.1 seconds to 0.5 seconds.

Compared with the respiratory rate of a human being of about 6 exhalations per minute to 24 exhalations per minute (corresponding to 0.1 to 0.4 exhalations per second), the device for determining the concentration of at least one gas component in a respiratory gas mixture proposed by the invention enables a temporal measurement resolution which makes it possible, in combination with a suitably selected sampling rate, to detect concentration changes in the respiratory gas as measurement data of the respiratory breakdown.

In general, but also for so-called "mainstream measurements", for example in the form of the aforementioned tees as a guide for the secondary or side stream, the structural dimensions play a more important role, since owing to the spacing not only a smaller measurement volume can be achieved, but also the optical path length between the detector element and the radiation source can be kept small. This depends on the fact that the measurement data can be detected at a detector element with sufficient signal level with good signal-to-noise ratio (SNR), so that a high measurement sensitivity in terms of powerful signal quality is achieved, which in combination with a matched amplifier circuit and a high-quality analog-to-digital converter (a/D converter) can provide a high measurement resolution that is noise-free to a greater extent, for example with 16-bit or finer (20-bit, 24-bit) bit quantization.

By the measurement channel overlapping the reference channel, it is advantageously achieved that detected measurement data of the distinguished expiration, which can be obtained directly in time with the actual physical measurement, have an effect which influences the measurement channel and the reference channel in a manner similar, for example, to the measurement of gas temperature changes, contaminants, water vapor, moisture, contaminants of the radiation source or of the reflector element, without the need for laborious further signal processing or measurement data correction, for example, on the basis of externally supplied moisture and/or temperature data.

The embodiments described represent specific embodiments of the device for determining the concentration of a gas component in a breathing gas mixture on its own and in combination or in combination with one another. Although not all possible combinations of the embodiments are described in detail here, all and possibly further embodiments and advantages thereof resulting from a combination or a plurality of embodiments are still within the scope of the inventive concept.

Drawings

The invention will now be explained in more detail with the aid of the following figures and the attached description of the figures, without limiting the general inventive concept. Shown in the figure are:

figure 1a is a first schematic view of an apparatus for concentration determination,

figure 1b is another second schematic view of a device for concentration determination,

FIG. 1c is a schematic illustration of a variant of the device for concentration determination according to FIG. 1a or 1b,

figure 2 is an arrangement of means for concentration determination on a flow-guiding element,

figure 3 is another arrangement of the device for concentration determination on a flow-guiding element,

fig. 4 is a flow-guiding element with a device for concentration determination.

Detailed Description

Fig. 1a shows a first schematic view of an apparatus 1 for determining the concentration of at least one gas component in a breathing gas mixture. The device 1 shown has a radiation source 30 with a radiation element 300. Opposite the radiation source 30, the

detector elements

50 and 60 are arranged with a vertical spacing l 333. The band-

pass filter elements

51, 61 are arranged at the

detector elements

50, 60. The band-

pass filter elements

51, 61 are preferably implemented as band-pass filter elements allowing a predetermined wavelength range of the radiation 31 radiated by the radiation source 30 to pass through. In this fig. 1a, a coordinate system with a vertical reference axis 32 and a horizontal reference axis 36 is drawn, which is referred to when describing the position of the components relative to each other and in space. Thus, the radiation 31 from the radiation source 30 radiates from a horizontal plane 37 of radiation, wherein the horizontal plane 37 is parallel to the horizontal reference plane 36.

A control unit 9 is provided which is connected to the radiating element 300 by means of control lines 93, 93'. Furthermore, the control unit 9 is connected to the detector elements 60 by means of

control lines

96, 96'. The control unit 9 is furthermore connected to the detector elements 50 by means of control lines 95, 95'. The detector element 50 and the associated filter element 51 together form an angle component 52. The detector element 60 and the associated filter element 61 together form an angle component 62. Together, the

angle components

52 and 62 form a detector assembly 40 which, in cooperation with the radiation source 30 and the control unit 9, functionally forms the device 1 for concentration determination of gas components. The arrangement of the probe assembly 40 relative to the vertical axis 32 and the horizontal reference axis 36 is determined by the spacing and angle of the

angle assemblies

52, 62.

In this fig. 1a, the angle assembly 52 is designed in a parallel arrangement with the horizontal reference axis 36 and the horizontal plane of radiation 37. Thereby resulting in an angle α 153 of the angle assembly 52 of 90 ° from the vertical reference axis 32. A horizontal spacing l 134 of the detector elements 50 relative to the central axis 32 is produced in the detector assembly 40. A spacing l 134' for the detector elements 60 relative to the central axis 32 is produced in the detector assembly 40. The spacing l 235 of the band pass filter elements 51 relative to the central axis 32 is obtained in the detector assembly 40. In the detector arrangement 40, a spacing l 235' for the filter element 61 relative to the central axis 32 is furthermore obtained. The spacing l 134 and l 235 of the filter element 51 from the central axis 32 is identical for the detector element 50, as a result of the arrangement of the angle arrangement 52 at an angle of 90 ° to the central axis 32.

The angle assembly 62 is designed to be at an angle alpha relative to the central axis 32₂63 are inclined. Angle alpha ₂63 is defined here in an angular range which is significantly smaller than 90 deg. relative to the central axis 32. Due to the angle assembly 62 with the detector element 60 and the filter element 61 being at the angle alpha ₂63 is tilted for radiation 31 radiated by the radiation source 30 along a vertical spacing l between the radiation source 30 and the detector assembly 40₃33 creating an overlap region 65 in said radiation 31. This overlap region 65 is produced perpendicularly from the plane of the angle assembly 62 in the direction of the radiation source 30. Due to the angle alpha ₁53 and alpha ₂63, for example for gas molecules or condensates (such as water vapor or water) depicted in this fig. 1a, for example on the central axis 32 in the vicinity of the radiation source 30Drop) 400, it being the case that the radiation 31 of the radiation source penetrates the gas molecules 400, and the radiation 31 here acts both on the detector element 50 and on the detector element 60. It is thus ensured that, for example, moisture (condensate) 400 attenuates the radiation in the same manner both at the detector element 50 and at the detector element 60. This creates the possibility of eliminating the influence of moisture from the proportional formation of the signals of the

detector elements

50 and 60. Can pass through an angle alpha ₁53 and alpha ₂63 to define the region of overlap, and the angle relative to the vertical central axis 32. Incorporating a vertical spacing l between the radiation source 30 and the detector assembly 40₃33, the dimensions of the overlap region 65 are further defined.

The control unit 9 evaluates the signals of the

detector elements

50, 60 by means of suitable electronic components 11 (amplifiers, similar to digitizers, microcontrollers) and provides an output signal 99. The output signal 99 here represents the signals detected by the

detector elements

50, 60 and the ratio of the detected signals, and thus also the gas concentration derived from these signals or signal ratios.

Fig. 1b shows a further second schematic view of a device 1' for determining the concentration of at least one gas component in a breathing gas mixture. Like elements in fig. 1a and 1b are identified in fig. 1b with the same reference numerals as corresponding like elements in fig. 1 a.

Fig. 1b shows a modified variant of fig. 1a with a further second illustration. In contrast to fig. 1a, in fig. 1b the radiation source 30 is arranged on the same side as the optical elements and the detector. The device 1' shown has a radiation source 30 with a radiation element 300. A detector element 50 and a further detector element 60 are arranged directly adjacent to the radiation source 30. On the

detector elements

50, 60, band-

pass filter elements

51, 61 are arranged. A reflector 39, for example a flat mirror, is arranged as a reflective optical element opposite the radiation source 30. The reflector 39 acts as a mirror for the radiation 31 emitted by the radiation source 30 and reflects the reflected radiation 31' to the band-

pass filter elements

51, 61 and to the

detector elements

50, 60. The band-

pass filter elements

51, 61 allow light to pass within a predetermined wavelength range. In this fig. 1b, a coordinate system with a vertical reference axis 32 and a horizontal reference axis 36 is depicted. These axes are used in a manner similar to that described in relation to fig. 1a with respect to the position of the components relative to each other and in space. A control unit 9 is provided, which is connected to the radiation elements 300 of the radiation source 30. The arrangement for connecting the control unit 9 to the

detector elements

60, 50 by means of the

control lines

93, 93' or 96, 96' and 95, 95' corresponds to the arrangement according to fig. 1a and the corresponding description, which will be mentioned later for this purpose. The detector element 50 and the associated filter element 51 together form an angle component 52. The detector elements 60 form an angle component 62 with the associated filter elements 61. These

angle elements

52, 62 form, together with the radiation source 30, a detector element 41 which, in combination with the control unit 9 and the reflector 39, functionally forms a device 1' for concentration determination of the gas components. The arrangement of the probe assembly 41 about the

axes

32, 36 is determined by the spacing and angle of the

angle assemblies

52, 62. The horizontal spacing l 134 of the detector elements 50 relative to the central axis 32 is obtained in the detector assembly 41. A spacing l 134' for the detector elements 60 relative to the central axis 32 is obtained in the detector assembly 41. The spacing l 235 of the band-pass filter element 51 with respect to the central axis 32 is obtained in the detector assembly 41. In the detector arrangement 41, a spacing l 235' for the filter element 61 relative to the central axis 32 is also provided.

In this fig. 1b, the

angle components

52, 62 are embodied relative to the central axis 32 at an angle α to the central axis 32, respectively₁53 and alpha ₂63 are inclined.

Here, the angle α ₁53 and angle alpha ₂63 have an angular extent of significantly less than 90 deg. relative to the central axis 32. Angle alpha ₂63 and alpha ₁53 are designed, for example, in this fig. 1b with different angular dimensions, a₂63 and alpha ₁53 may also be designed to have the same angular dimension with respect to the central axis 32, which is also included in the concept of the present invention. Due to the angle α of the angle component 52 with the detector element 50 and the filter element 51₁53 ofThe angle assembly 62, which is inclined and has the detector element 60 and the filter element 61, is at an angle α₂The inclination of 63, after reflection by means of reflector 39, results in an overlap region in the reflected radiation 31' for the radiation 31 emitted by the radiation source 30 along the vertical spacing between the radiation source 30 and the detector assembly 41. The

angle components

52, 62 are designed with respect to the horizontal reference axis 36, the central axis 32 and a light-reflecting horizontal plane 37' arranged parallel to the horizontal reference axis 36. The overlap region obtained on the basis of the

angle components

52 and 62 leads, for example, to the influence of contaminants or condensation present in the reflected radiation 31 in the vicinity of the reflector 39, i.e. to attenuation of the radiation if necessary, to the detector element 50 and to the detector element 60 in the same way. This creates the possibility of eliminating the influence of moisture 400 (fig. 1 a) or contaminants from the ratio of the signals of the

detector elements

50 and 60 as described for fig. 1 a. Can pass through an angle alpha ₁53 and alpha ₂63 define an overlap region with respect to each other and with respect to the selection of the perpendicular central axis 32. In contrast to fig. 1a, fig. 1b shows a path of the radiation 31 to the reflector 39 and a reflected path of the reflected radiation 31' to the

detector elements

50, 60 in the simplest case of an elongated, dual radiation path. This has the result that the intensity of the light beam emerging onto the

detector elements

50, 60 is smaller than in fig. 1 a. This results in a difference in the sensitivity of the device 1' for determination of the concentration of the gas component in this fig. 1 b. The signals of the

detector elements

50, 60 are evaluated in the control unit 9 by means of suitable electronic components 11 in a similar manner as described with reference to fig. 1 a. The control unit provides an output signal 99 representing the signal of the

detector elements

50, 60 and a ratio of the signals representing the

detector elements

50, 60. Thus, output signal 99 provides a gas concentration derived from the signal based on the signal detected by

detector elements

50, 60 for further processing, such as display unit 94 (FIG. 2).

Fig. 1c shows a schematic representation of a variant of the device for concentration determination according to fig. 1a or 1 b. Like elements in fig. 1a, 1b and 1c are identified in fig. 1c with the same reference numerals as corresponding similar elements in fig. 1a and 1 b.

Fig. 1c shows a modification according to fig. 1a or 1 b. Fig. 1a and 1b show two basic variants of the design of the

detector elements

50, 60, the radiation source 30 and the reflector 37, with or without connection. Fig. 1c is intended to show a variant in which not only two

detector elements

50, 60 are arranged as a device for measuring gas, but also a total of more than two detector elements are arranged on each other in a circular or rectangular design. Such a design with a plurality of detector elements makes it possible to carry out measurements with a plurality of measurement gases, for example three or more gases, by reference to three or more detector elements assigned to the measurement gas by means of the detector elements. As a geometric design, a funnel in the form of a frustum higher than the head, constituting a rectangular or square base or surface with blunt portions, is shown in fig. 1 c.

For this purpose, fig. 1c is designed in the following way:

a total of four

angle elements

52, 62, 72' are constructively designed around the center point 2 in an arrangement inclined at an angle α 152, α 262, α 373, α 3' 73' relative to the center axis 32. In this fig. 1c, the horizontal axes 36 and 36 'and the vertical axis 32 are shown in the arrangement of the

angle assemblies

52, 62, 72', respectively, in order to make this spatial configuration clearly visible in this fig. 1 c. The axes 32, 32', 36' here show the same spatial coordinate system as in fig. 1a and 1 b.

In the embodiment according to fig. 1b with a device 1 'for determining the concentration of a gas component, as shown in fig. 1c, the radiation source 30 is arranged centrally between the

angle elements

52, 62, 72' in a dashed-line guided manner. Not shown in fig. 1c, a reflector element is also required opposite the radiation source 30. In one such embodiment, as can be seen in fig. 1b, a reflector 39 (fig. 1 b) is arranged on the wall opposite the radiation source 30, said wall having a light-reflecting horizontal plane 37' (fig. 1 b). The radiation source 30 is shown here directly at the center point 2 by means of a radiation element 300, here indicated in a dashed-line guided manner as a spiral.

In the embodiment of fig. 1c with a device 1 for determining the concentration of the gas component according to fig. 1a, the radiation source 30 at the center point 2 is omitted. In such a configuration, the radiation source would be arranged opposite the

angle assembly

52, 62, 72', and the region around the center point 2 would have no measuring-technical or optical components (52, 62, 72', 30). Alternatively, a design can be made in which the region around the central point 2 does not remain free. A design can then be implemented as a variant, in which case further angle components can be implemented there. This further angle component is not embodied in detail in this fig. 1c, but comprises all features with detector elements and filter elements and is arranged as reference detector element flush with the horizontal plane 36 or 36'. Such further angle components may for example be used to provide a reference signal. This results in a variant in which four, rather than three different, gases can be detected with the

angle arrangement

52, 62, 72' with respect to a reference detector element which is arranged centrally between the remaining four detector elements. Thus, with the reference detector elements, the interference due to the common overlap region 65 (fig. 1 a) of the reference detector elements with all four

angle components

52, 62, 72', which is drawn for the sake of illustration in this fig. 1c, is compensated.

This advantageously results in an embodiment in which disturbances, contaminants, condensates and other contaminants present in the radiation act equally on all three measurement signals and the reference signal, so that an optimum compensation of these influences is obtained.

Fig. 2, 3, 4 show the arrangement of the device for determining the concentration at the flow-guiding element according to fig. 1a, 1b, 1 c. Fig. 2, 3 and 4 are to be understood in the common figure description with respect to the same features as one another, but also with respect to the differences from one another.

Like elements in fig. 2, 3, 4 and 1a, 1b, 1c are denoted in fig. 2, 3, 4 by the same reference numerals as the corresponding like elements in fig. 1a, 1b, 1 c.

Fig. 2 shows a device 1' for determining the concentration of a gas component (fig. 1 b) in a flow-guiding element 100. The flow-guiding element 100 is designed to supply a flow with a gas quantity 80 to the measuring section by means of the device 1' (fig. 1 b). The

angle modules

52, 62 are shown in connection with the radiation source, the radiation element and the control unit 9. The

angle assembly

52, 62 with the radiation source and the control unit 9 is arranged in a holding element 97 which can be coupled to a flow-guiding element 100 by means of a sealing element 98. The arrangement according to fig. 2 functions as described in fig. 1 b.

Fig. 4 shows an arrangement comparable to fig. 2 in a flow channel 100 ″ having a device 1' for determining the concentration of a gas component. Here, there is also a retaining element 97 which is inserted into the flow-guiding element 100 ″ by means of a sealing element 98. In the flow-guiding element 100 ″ in contrast to fig. 2, in fig. 4 only a partial amount in the form of a side or side stream of the gas quantity flowing in the flow-guiding element 100 ″ reaches the device for determining the concentration of the gas component 1' (fig. 1 b). Fig. 4 thus shows the measurement in the so-called bypass. In this fig. 4, a reflector 39' is shown in this case in an arched embodiment, which is arranged as part of a holding element 97, also opposite the radiation source 30 as in fig. 2.

In this fig. 4, the installation of the holding element 97 as an insert into the flow-guiding element 100 ″ in the form of a T-piece makes it possible for the device 1' (fig. 1 b) for measuring the concentration of the gas component in the secondary or side stream in the bypass to be arranged almost in the flow center of the flow-guiding element 100 ″, that is to say essentially in the center of the flow-guiding element 100 ″, and is effective in terms of measurement technology. Alternatively and additionally, the arrangement of the holding element 97 is also shown explicitly with this fig. 4, wherein the device 1' (fig. 1 b) for the concentration test of the gas component is not arranged in the flow center, but in the edge region of the flow-guiding element 100 ″ and is effective in terms of measurement technology. This results in a design of the bypass in the edge flow region in the edge region of the flow-guiding element 100 ″.

In contrast to fig. 2 and to fig. 4, in fig. 3, the device 1 for determining the concentration of a gas component according to fig. 1a is shown in a flow channel 100'. The radiation source 30 is arranged on the flow-guiding element 100' relative to the two

angle mechanisms

52, 62. The angle means 52, 62 are arranged opposite the radiation source 30 at the position of the flow-guiding element 100, at which the flow cross section in the form of a venturi tube decreases. In this embodiment according to fig. 3, the elements of the control unit 9 are arranged from both sides. This makes it possible to operate not only the

angle mechanism

52, 62 with the detector elements 50, 60 (fig. 1 a) but also to enhance the signal. Additionally, the control unit 9 is used to operate the radiation source 30 and to output an output signal 99.

In fig. 2, 3 and 4, an output signal 99 is provided, which represents the detected gas concentration, as was previously carried out in fig. 1a and 1 b.

In contrast to fig. 4, fig. 3 and 2 are embodied in such a way that the measurement of the gas concentration of the gas quantity 80 is not carried out in the bypass flow but directly in the main flow. In fig. 2, a medical instrument 200 and a display unit 94, each as an optional component, are depicted in dashed lines. These optional components represent exemplary possibilities for further conveying the output signal 99 to further processing and application.

These

optional components

200, 94 are not shown in fig. 3 and 4, but should nevertheless be regarded as being included in the design according to fig. 3 and 4 in the light of the inventive concept.

List of reference numerals

1. 1' device for determining the concentration of a gas component

2 midpoint (intersection of axes 32 'and 36')

9 control unit

11 electronic component

30 radiation source

31 radiation

31' reflected radiation

32. 32' vertical axis, central axis, reference axis are vertical

33 l3, l3' vertical spacing

34 l1 spacing of the detector elements 50 relative to the central axis 32

34' l1 spacing of detector elements 60 relative to central axis 32

Spacing of 35 l2 filter elements 51 with respect to the central axis 32

Spacing of 35' l2 filter elements 61 relative to central axis 32

36. 36' horizontal reference axis

37 horizontal plane of radiation

37' horizontal plane of light reflection

38 wall

39. 39' reflector, mirror element

40 Detector Assembly

41 detector assembly, reflective

50 detector element

51 band pass filter element

52-degree assembly

53 Angle α 1

60 detector element

61 band pass filter element

62 degree angle subassembly

63 Angle alpha 2

65 overlap region

72 degree angle assembly

72' angle assembly

73 angle alpha 3

73 'Angle alpha 3'

80 amount of gas and gas concentration

93. 93' control line to 300 of the radiating element

94 display unit

95. 95' data line and signal line

96. 96' data line, signal line

97 holding element

98 insert, sealing element

99 output signal

100. 100', 100' ' flow guide element

200 medical instrument, breathing machine and anesthesia machine

300 radiating element (film, helix)

400 gas molecules, condensate

Claims

1. Device for determining the concentration of a gas component (1, 1') in the inspired or expired gas of a living being, having:

-a radiation source (30) adapted and designed for radiation (31) of optical or thermal radiation in the direction of radiation in the wavelength range lambda l (λ 1) =2.5 μm to lambda2 (λ 2) =14.0 μm,

a detector assembly (40, 41) with at least two detector elements (50, 60) suitably configured for detecting optical or thermal radiation generated by the radiation source (30),

at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60),

a control unit (9) for controlling the operation of the radiation source (30) and for signal detection of the at least two detector elements (50, 60),

wherein at least one of the at least two band-pass filter elements (51, 61) is constructed to be optically transparent to infrared radiation, which is absorbed by the measurement gas,

wherein at least one of the at least two band-pass filter elements (51, 61) is configured to be optically transparent to infrared radiation for radiation that is not absorbed by the measurement gas,

wherein at least one of the two detector elements (50, 60) with at least one of the at least one band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60) is arranged in an angle assembly (52, 62) at an angle (53, 63) in the range of 20 ° to 80 ° relative to an axis (32) running through the radiation source (30) parallel to or in the same direction as the radiation (31) of the radiation source, wherein each of the at least two detector elements (50, 60) is arranged at a first spacing l1 (34, 34') relative to a vertical axis (32) extending between the at least two angle assemblies (52, 62), the first spacing being in the range of 0.1mm to 10.0mm,

wherein each of the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60) is at a second spacing l relative to a perpendicular axis (32) extending between the at least two angle components (52, 62)₂(35) Is arranged with a second distance in the range of 0.1mm to 10.0mm, wherein the detector assembly (41) with the at least two detector elements (50, 60) and the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60) is arranged with a third distance/₃(33) Arranged opposite the radiation source (30), the third distance l₃In the range of 0.1mm to 10.0mm, wherein the third pitch i₃(33) A distance in the region of the axis (32) extending directly between the at least two angle components (52, 62) or a distance along the axis (32) extending between the at least two angle components (52, 62), wherein the radiation source (30) is arranged centrally on the axis (32) extending between the at least two angle components (52, 62) between the at least two detector elements (50, 60) with the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60), wherein the band-pass filter elements (51, 61, 71, 81) thereof are designed for penetrating infrared light in a penetration range having a wavelength range of 2.5 μm to 14 μm.

2. Device for determining the concentration of a gas component (1, 1') in the inspired or expired gas of a living being, having:

wherein each of the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60) is arranged opposite theretoA second distance l of the vertical axis (32) extending between the at least two angle assemblies (52, 62)₂(35) Arranged with the second pitch in the range of 0.1mm to 10.0mm, wherein the detector assembly (40) with the at least two detector elements (50, 60) on the same side and the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60) is arranged adjacent to the radiation source (30),

wherein a third distance l is provided opposite the radiation source (30) and opposite the at least two detector elements (50, 60) with the at least two band-pass filter elements (51, 61) arranged on the at least two detector elements (50, 60)_3'At least one optically reflective, planar element (39) is arranged, the third distance l_3'In the range of 0.1mm to 5.0mm, wherein the third pitch l_3'A distance in the region of the axis (32) extending directly between the at least two angle components (52, 62) or a distance along the axis (32) extending between the at least two angle components (52, 62), wherein the band-pass filter element (51, 61, 71, 81) thereof is designed for penetrating infrared light in a penetration range of a wavelength range of 2.5 μm to 14 μm.

3. The device (1) according to claim 1 or 2, wherein the band-pass filter element (51, 61, 71, 81) is designed for optically filtering infrared light in a transmission range of a wavelength range of 2.5 μm to 14 μm.

4. The device (1) according to claim 1 or 2, wherein the radiation source (30) is constructed as a surface emitter, a thin film emitter or as a radiation element (300) with a planar designed radiation surface or as a Light Emitting Diode (LED) with a planar designed radiation surface, wherein the radiation surface is designed for a uniform radiation (31) over the radiation surface.

5. The device (1) according to claim 1 or 2, wherein the detector element (50, 60) is designed as a pyroelectric detector, as a bolometer, as a semiconductor detector, as a thermopile or as a thermocouple.

6. The device (1) according to claim 1 or 2, wherein the detector arrangement (40) has more than two angle arrangements (52, 62, 72') with detector elements and band-pass filter elements, which are arranged in a spatial arrangement around the center point (2) in the form of the sides of a rectangular or square frustum.

7. The device (1, 1 ') according to claim 1 or 2, wherein the detector assembly (40, 41) together with the radiation source (30) is configured as a flow guiding element (100, 100 ') adapted for guiding inhaled and/or exhaled gas, such that the measurement gas flows as a main flow through the flow guiding element (100, 100 ') and the gas concentration can be detected in the main flow.

8. The device (1) according to claim 1 or 2, wherein the detector assembly (40) together with the radiation source (30) is configured as a member (97) of a flow guide element (100 ") for guiding inhaled and/or exhaled gas such that the measurement gas representing the amount of gas flowing through the member (97) as a part of the main flow in the center of the flow guide element (100) as an additional or side flow in which the amount of gas can be detected is used for concentration measurement.

9. The device (1) according to claim 1 or 2, wherein the detector arrangement (41) together with the radiation source (30) is configured as a component (12) arranged laterally in a flow-guiding element (100 ") adapted to guide inhalation and/or exhalation gases, such that the measurement gas, which represents the amount of gas flowing through the component (12) in a lateral edge region of the flow-guiding element (100") as part of a main flow in a side flow or side flow in which the amount of gas can be detected, is used for concentration measurement.